Controllable current source for a phase locked loop

US7495485B2 · kind B2 · utility

Assignee

• National Semiconductor Germany AG · DE

Inventors

• Christophe Holuigue · Birkenfeld, DE
• Martin Gröpl · Sonthofen, DE

Key dates

• Filing date: Apr 17, 2007
• Grant date: Feb 24, 2009
• Expiry date: Apr 17, 2027

Classification

• Technology area (CPC H): Electricity
• CPC primary: H03L7/0896
• WIPO field: Control
• WIPO sector: Instruments

Abstract

The invention concerns a controllable current source or “charge pump” (12) in an integrated circuit, comprising two supply terminals (K1, K2) for the application of two supply potentials (V1, V2) as well as an output terminal (Kout) for the delivery of an output current, connected via a first controllable current path (T1) with the first supply terminal (K1), and via a second controllable current path (T2) with the second supply terminal (K2). In order to improve the current source (12) with regard to the quality of the output signal, it is provided according to the invention that the controllable current source (12) furthermore has a replica (T1′, T2′) of the current paths (T1, T2) in their non-controlled state, of which a replica output terminal (Kout′) is connected via a current mirror (T5 to T8) with the output terminal (Kout).